Rinnai · Tankless water heater

ON Hot water running (controller installed)

Normal status KCM (RUCS/RUS)

What the display is showing

On a KCM unit with a temperature controller, the status monitor shows ON while hot water is being supplied. Normal operation.

Applies to: Rinnai KCM tankless (RUCS65i/75i, RUS65e/75e) status monitor

Settings for these units

RSC supply connection sizes · SENSEI
RSC water quality limits · SENSEI
RSC clearances to combustibles · SENSEI
RSC temperature settings available · SENSEI
RX supply connection sizes · SENSEI RX/CX
RX water quality limits · SENSEI RX/CX

Other codes on the same units

Diag history Maintenance code history viewer (last 9 codes)
FH Forced high-fire combustion
FL Forced low-fire combustion
LOC Controller locked (KCM)
Maint monitor KCM maintenance monitor (flow and outlet temperature)
Mute Controller key beeps on/off
Priority light Priority light on (this controller is in charge)
°C/°F Temperature scale switch (Celsius / Fahrenheit)

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Source: Rinnai KCM Series Manual (U328-0700X04), Diagnostic Information (status monitor) p.56. Summarized in our own words; check the original manual for your model.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.